Batch dishwashers are manually loadable and unloadable dishwashers. Batch dishwashers (also referred to as “box-type warewashers”) may be a dish-rack-type pass-through dishwasher, also referred to as hood-type dishwashers (“hood-type warewashers”) or front loaders (“front loader warewashers”). Front loaders may be undercounter machines, countertop machines or free-standing dishwashers with front loading configuration (“free standing front loaders”).
A dishwasher in the form of a batch dishwasher normally has a treatment chamber for the cleaning of items of washware. In general, below the treatment chamber, there is arranged a wash tank into which liquid can flow back from the treatment chamber under the action of gravitational force. In the wash tank there is situated wash liquid, commonly water, to which detergents may be added if appropriate.
A dishwasher in the form of a batch dishwasher normally furthermore has a wash system with a wash pump, with a line system connected to the wash pump, and with a multiplicity of spray nozzles formed on at least one wash arm. The wash liquid situated in the wash tank can, by way of the wash pump, be delivered via the line system to the wash nozzles and sprayed through the wash nozzles in the treatment chamber onto the items of washware to be cleaned. The sprayed wash liquid subsequently flows back into the wash tank.
A dishwasher of said type in the form of a batch dishwasher is known for example from the document DE 10 2005 023 429 A1.
The expression “washware” used herein is to be understood in particular to mean dishes, glasses, cutlery, cooking utensils, baking utensils and serving trays.
The invention relates in particular to a dishwasher in the form of a commercial utensil washer or dishwasher which is designed as a batch dishwasher and is preferably realized as a front-door dishwasher, wherein the dishwasher has a treatment chamber with at least one wash system, which is designed as a recirculation system.
Dishwashers of said type are used primarily (but not exclusively) in relatively small sculleries, for example in the case of relatively small cafeterias, in particular school cafeterias, or in the catering sector. What is characteristic of the use of such dishwashers is that they are used in sculleries in which, in general, only a limited installation area is available.
A commercial dishwasher in the form of a batch dishwasher differs from a domestic dishwasher in particular in that a commercial dishwasher must be designed such that—depending on the selected treatment programme—programme running times of between one and five minutes can be realized, whereas domestic dishwashers generally have running times of up to 2.5 hours or longer. Owing to the short programme duration that is required in the case of commercial dishwashers, techniques used in domestic dishwashers generally cannot be readily transferred to commercial dishwashers.
Commercial dishwashers in the form of batch dishwashers normally operate in two main process steps: a first step, which comprises washing using a wash liquid, and a second step, which comprises final rinse using heated freshwater and dosed rinsing agent.
To be able to perform these process steps, a commercial dishwasher in the form of a batch dishwasher is generally equipped with two independent liquid systems. One liquid system is a wash water circuit which is responsible for the washing of the items of washware, wherein the washing is performed using recirculated water from the wash tank of the dishwasher. The other liquid system is a fresh water system which is responsible for the final rinse. The final rinse is performed using fresh water, preferably with fresh water from a water heater (boiler). The freshwater, after being sprayed, is likewise received in the wash tank of the dishwasher.
It is the main object of the final rinse to remove soapy water situated on the items of washware. Furthermore, the final rinse water that flows into the wash tank during the final rinse step serves for the regeneration of the wash water present in the wash tank.
Before fresh water as final rinse liquid is sprayed and is thus conducted into the wash tank of the dishwasher as a result of the final rinse process, an amount of wash liquid equivalent to the fresh water amount is pumped out of the wash tank.
Normally, commercial dishwashers in the form of batch dishwashers are equipped with multiple programmes. Said programmes differ primarily in terms of different lengths of programme running times of the washing process. The operator has the option to select a short wash programme in the case of lightly soiled items of washware or to select a correspondingly longer wash programme in the case of heavily soiled items of washware.
Commercial dishwashers which are in the form of batch dishwashers and which are designed for the batchwise loading and unloading of the treatment chamber with items of washware are in particular front-door machines or rack-type pass-through machines. In the case of front-door machines, the items of washware are placed into a rack, and the rack laden with items of washware is placed into the treatment chamber of the dishwasher through a front door and, after the cleaning process, is removed again through the front door. In the case of rack-type pass-through machines, the dish racks laden with items of washware are pushed manually into the treatment chamber from an entrance side and, after the end of a wash programme, are manually removed from the treatment chamber at an exit side. Front-door machines and rack-type pass-through machines comprise only a single treatment chamber for the treatment of the items of washware. Front-door machines may be undercounter machines or countertop machines.
Almost without exception, commercial dishwashers which are in the form of batch dishwashers and which are designed for the batchwise loading and unloading of the treatment chamber with items of washware are designed with infeed and/or run-out tables. On the infeed side of the dishwasher, it is normally the case that manual clearing and manual pre-washing of the soiled items of washware are performed. Furthermore, here, the soiled items of washware are loaded into special dish racks. The run-out side serves for the drying and unloading of the dish racks.
Commercial batch dishwashers, in particular those in the form of hood-type dishwashers, are designed for cleaning large amounts of items of washware in as short a time as possible. In the case of hood-type dishwashers that are common nowadays, the duration of a preset standard programme, which is commonly used for normally soiled items of washware such as plates, bowls, cups and glasses, is only approximately 60 to 80 seconds. This yields a theoretical capacity of up to 45 to 60 racks per hour.
Depending on the items of washware and the level of soiling thereof, it may however be necessary to select a treatment programme with a longer duration in order to ensure a flawless cleaning result.
In this context, it is known from the prior art that commercial batch dishwashers have, for example, a special cutlery treatment programme (intensive treatment program) for improving the cleaning result specifically of cutlery. Such an intensive treatment programme lasts much longer than the abovementioned 60 to 80 seconds of the standard treatment program, for example approximately 360 seconds. It is thus clear that the capacity of the machine is greatly reduced if an intensive treatment programme is selected, because the treatment chamber is then occupied for much longer than would be the case with a standard treatment program.
In practice, this has the effect that special treatment programmes, which are normally provided as standard as an alternative to the standard treatment program, are generally, despite the improved washing performance, selected only seldomly by the operator of the dishwasher because the corresponding programme duration is considered to be too long, in particular in busy periods, that is to say during periods in which increased amounts of items of washware are encountered. Instead, it is often the case that the heavily soiled items of washware (in particular cutlery and GN containers) are likewise treated using the standard treatment program, and the low washing performance is compensated for by way of additional manual working steps, for example manual prewashing of heavily soiled GN containers, or separate pre-soaking of cutlery.
In the case of relatively heavily soiled items of washware, such as commonly the case, for example, with pots or pans, it is necessary in particular for the cycle length to be correspondingly increased in order to be able to achieve a flawless cleaning result. Normally, in the case of hood-type or pass-through dishwashers, the programme running time is lengthened to up to 10 minutes in order to be able to clean heavily soiled items of washware, in particular pots and pans with burnt-on food residues, in a hygienically flawless manner.
During said lengthened cycle times, the dishwasher consequently cannot be used for cleaning less heavily soiled items of washware, such as for example plates, cups, cutlery or glasses. In other words, for the cleaning of heavily soiled items of washware, in particular pans and pots, the dishwasher is blocked for a relatively long time, which in the case of relatively small sculleries, often leads to problems, because during this time, the soiled dishes that accumulate cannot be cleaned or processed further.
In practice, it is therefore the case in particular in busy periods that the dishwasher is used only for the cleaning of lightly soiled items of washware, such as for example plates, cups and glasses, whereas the heavily soiled washware (in particular pots and pans) are manually cleaned in order to prevent the dishwasher from becoming blocked for an excessively long time owing to the required longer cycle times.